Problem Statement

There are $N$ cities on a number line. The $i$-th city is located at coordinate $x_i$.

Your objective is to visit all these cities at least once.

In order to do so, you will first set a positive integer $D$.

Then, you will depart from coordinate $X$ and perform Move $1$ and Move $2$ below, as many times as you like:

• Move $1$: travel from coordinate $y$ to coordinate $y + D$.
• Move $2$: travel from coordinate $y$ to coordinate $y - D$.

Find the maximum value of $D$ that enables you to visit all the cities.

Here, to visit a city is to travel to the coordinate where that city is located.

Constraints

• All values in input are integers.
• $1 \leq N \leq 10^5$
• $1 \leq X \leq 10^9$
• $1 \leq x_i \leq 10^9$
• $x_i$ are all different.
• $x_1, x_2, ..., x_N \neq X$

Input

Input is given from Standard Input in the following format:

N X
x_1 x_2 ... x_N

Output

Print the maximum value of $D$ that enables you to visit all the cities.